A three-dimensional (3D) multi-layer memory array is constructed with a plurality of ridge-shaped multi-layer stacks parallel to each other. As dimensions of the 3D multi-layer memory array scale down, the density of the multi-layer stacks increases, and the aspect ratio (i.e., the ratio of height to width) of the multi-layer stacks increases. Manufacture of the ridge-shaped multi-layer stacks with increased aspect ratio presents various challenges.